Evaluating putative ecological drivers of microcystin spatiotemporal dynamics using metabarcoding and environmental...

Area of Science:

• Environmental Science
• Ecotoxicology
• Microbiology

Background:

• Microcystin is a widespread cyanobacterial hepatotoxin. Understanding its environmental drivers is key for managing harmful algal blooms and minimizing exposure risks.
• Previous studies have explored various factors influencing microcystin production, but no single factor reliably predicts concentrations in complex aquatic ecosystems.

Purpose of the Study:

• To identify the key ecological drivers explaining spatiotemporal variations in microcystin concentrations in a freshwater reservoir.
• To determine which factors best predict the population dynamics of the cyanobacterial genus Microcystis.

Main Methods:

• Random forest regression analyses were employed using 16S and 18S rRNA gene sequencing data alongside environmental variables.
• The study focused on total microcystin and specific congeners, particularly MC-LR, in a eutrophic freshwater reservoir.

Main Results:

• Random forest models best predicted the congener MC-LR, explaining approximately 88% of the spatiotemporal variance.
• The relative abundance of the cyanobacterial genus Microcystis was the most significant factor associated with MC-LR concentrations.
• Factors influencing MC-LR concentrations were also found to be critical in predicting Microcystis population dynamics.

Conclusions:

• The abundance of Microcystis is a primary predictor of microcystin concentrations, especially MC-LR, in freshwater reservoirs.
• Ecological factors driving Microcystis dynamics are closely linked to microcystin production, offering insights into toxin function.
• These findings support the development of targeted lake management strategies focused on controlling Microcystis populations to mitigate harmful microcystin exposures.